I'll walk back my criticism a little bit, since it appears now that the Mac Pro RAM will be user-upgradable, at least.
But my main points stand. For a "professional" machine at the price that this thing will go for, one should not have to:
1. Shell out additional cash for a CD drive, expensive external hard drives, Thunderbolt dock, and/or PCIe chassis when the need arises. The only way this severe curtailing of expandability can be justified is if the machine itself is significantly cheaper than the current model, which is highly unlikely.
2. Deal with the clutter of all that external crap on one's desk. Tower cases were invented to clean up the mess of peripherals we had all over the place in the 80s and early 90s. They're a good concept, worthy of the market they're intended for, and shouldn't be thrown away just because some Apple engineers think circles are cool.
Actually, what I really worry about is the copycat designs this will spawn. PC manufacturers came out with some
truly horrendous case designs after the first iMac appeared.